What is diffusion?

Diffusion is the net movement of particles from an area of high concentration to an area of low concentration. This means that the particles of a substance move from where there is lots of it to where there is less, until eventually the particles are evenly spread throughout the liquid or gas. A good way to think of it is when you walk into a room where air freshener has been sprayed you smell it, this is because the particles have diffused from the area of high concentration (where it was sprayed) to an area of low concentration (the rest of the room).Diffusion is very important to allow substances to move in and out of cells. It is involved in a number of processes in the body including respiration.